Study on the microscopic fiber damage mechanism in carbon fiber reinforced polymer during single-grain scratching

Abstract

Carbon fiber reinforced polymer (CFRP) is an ideal lightweight material for a wide range of applications, including aerospace, due to its superior mechanical properties. In this study, a microscopic finite element model of CFRP is developed using the Finite Element Method to simulate the scratching process with a single grain. The fiber damage mechanism is investigated, and the effects of grain scratching speed, the depth of the surface fibers embedded in the matrix, and the depth of the grain cutting into subsurface fibers on the damage and removal of surface and subsurface fibers in CFRP are discussed. The results indicate that the formation of slanted fractures in fibers is closely associated with the initiation and propagation of central cracks, transverse cracks at both ends, and longitudinal cracks. With increasing scratching velocity, fiber damage exhibits a decreasing trend. No transverse cracks are observed in surface layer fibers at a scratching velocity of V = 120 m/s and in sub-surface fibers at V ≥ 90 m/s. Under scratching conditions of V ≥ 90 m/s, the damage in both surface and sub-surface fibers tends to be mitigated. This study provides new insights into the fiber damage mechanism of CFRP during grinding processes and offers a theoretical basis for optimizing grinding parameters and improving processing quality.